1. Field of the Invention
The present invention relates to a personal microwave and radio frequency (RF) detector. More particularly, the present invention relates to a self-contained personal microwave and RF detector which can be worn in a user's ear and provides an instantaneous audible warning of dangerously high electromagnetic fields.
2. Description of the Prior Art
Electromagnetic radiation hazards to personnel are presently detected by survey of an area with handcarried instruments, or instruments which are fastened to a user's clothing, to detect whether electromagnetic radiation in the area exceeds permissible exposure limits. For example, U.S. Pat. No. 5,168,265 to Aslan discloses a personal electromagnetic radiation monitor worn by a user who may be exposed to potentially harmful levels of electromagnetic energy in the 2-18 GHz frequency range. The Aslan monitor has a two piece housing with a resilient clip mounted on a back wall of the housing for allowing a user to carry the monitor on a belt or shirt pocket. A pair of mutually orthogonally disposed antenna elements receive electromagnetic energy for detection.
When detected electromagnetic energy is above a preset threshold, the Aslan monitor actuates a periodic audible warning tone with an increasing repetitive rate as the level of exposure increases. The Aslan monitor also includes an ear plug assembly allowing the monitor to be used in high noise environments. A hollow tube, having a pneumatic ear plug mounted on one, is coupled to the monitor housing. A warning tone produced by the monitor is transmitted to a user's ear through the tube of the ear assembly.
U.S. Pat. No. 4,539,567 to Brewer discloses another small personal microwave monitor device attached to the clothing of a user and adapted for use from 2-15 GHz. The Brewer monitor provides field alarms, field monitors, accumulated dose alarms and integrated dose monitoring of microwave radiation. Brewer discloses a variety of antenna configurations for permitting use at other frequencies, for example, between 0.9-2 GHz as well as 15-30 GHz.
U.S. Pat. No. 4,301,406 to Shriner discloses a microwave detector conveniently carried or worn by a user. One embodiment of the Shriner detector includes a very low-wattage gaseous-discharge lamp having electrodes connected to the ends of a pair of antenna wires. A second embodiment of the Shriner detector shaped like a fountain-pen. Yet another embodiment shaped like a bracelet or finger ring.
U.S. Pat. No. 4,032,910 to Hollway et al. discloses a portable detector for producing an alarm when placed in a microwave field having a power density greater than a predetermined limit. One embodiment of the Hollway detector includes a dipole antenna connected to filament leads of an incandescent lamp mounted on a card which can be pinned to the lapel of a user. An alarm is signalled by a glow from the lamp filament.
While these and other known microwave radiation detectors provide an indication of detection of a microwave field, there is still a need for a microwave and radio frequency (RF) detector which provides an instantaneous acoustical warning of dangerously high electromagnetic fields, permitting workers to perform their normal tasks while wearing protective equipment such as helmets, goggles, ear muffs, etc. Further, there is a need for a simple, compact, self-contained microwave and RF detector having long battery life and operates over an extremely broad band of frequencies, for example, 2 MHz to 22 GHz. Additionally, there is a need for providing a user with immediate knowledge of the presence of radar or RF transmitting devices operating in the vicinity of the user. Existing radar detection devices are comparatively large, externally worn, that is, worn on the user's clothing, and limited to operation at microwave frequencies.